Polyolefins prepared with metallocene catalysts having 2-substituted indenyl type ligands

ABSTRACT

&lt;DEL-S DATE=&#34;20010605&#34; ID=&#34;DEL-S-00001&#34;&gt;The novel metallocenes of the formula Iin which, preferably, M1 is Zr or Hf, R1 and R2 are alkyl or halogen, R3 and R4 are hydrogen, R5 and R6 are alkyl or haloalkyl, -(CR8R9)m-R7-(CR8R9)n- is a single- or multi-membered chain in which R7 may also be a (substituted) hetero atom, m+n is zero or 1, and R10 is hydrogen, form, together with aluminoxanes as cocatalysts, a very effective catalyst system for the preparation of polyolefins or high stereospecificity and high melting point.&lt;DEL-E ID=&#34;DEL-S-00001&#34;&gt;  &lt;INS-S DATE=&#34;20010605&#34; ID=&#34;INS-S-00001&#34;&gt;Polyolefins with unique or improved properties are obtained by polymerizing an olefin in the presence of a metallocene combined with a cocatalyst, wherein the metallocene is preferably a zirconocene or a hafnocene, and the Zr or Hf central atom is coordinated with two ligands which are derivatives of 2-substituted indenyl nuclei and which are substituted with at least one and up to four groups (e.g. aliphatic or aromatic groups) on the six-member rings of the indenyl nuclei. The indenyl nuclei are optionally substituted at the 3-position and are joined by a 1,1&#39;-bridge of the formula -(CR8R9)m-R7-(CR8R9)n-, which is a single- or multi-membered chain in which R7 can also be a (substituted) hetero atom, m and n are identical or different and are zero, 1, or 2, and m+n is zero, 1, or 2.&lt;INS-E ID=&#34;INS-S-00001&#34;&gt;

The present invention relates to novel metallocenes which containligands of 2-substituted indenyl derivatives and can very advantageouslybe used as catalysts in the preparation of polyolefins of high meltingpoint (high isotacticity).

Polyolefins of relatively high melting point and thus relatively highcrystallinity and relatively high hardness are particularly important asengineering materials (for example large hollow articles, tubes andmoldings).

Chiral metallocenes are, in combination with aluminoxanes, active,stereospecific catalysts for the preparation of polyolefins (U.S. Pat.No. 4,769,510). These metallocenes also include substituted indenecompounds. Thus, for example, the use of theethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconiumdichloride/aluminoxane catalyst system is known for the preparation ofisotactic polypropylene; cf. EP-A 185 918). Both this and numerous otherpolymerization processes coming under the prior art have, in particular,the disadvantage that, at industrially interesting polymerizationtemperatures, only polymers of relatively low melting points areobtained. Their crystallinity and thus their hardness are too low foruse as engineering materials.

Surprisingly, it has now been found that metallocenes which contain, asligands, certain 2-substituted indenyl derivatives are suitablecatalysts for the preparation of polyolefins of high isotacticity(melting point) and narrow molecular weight distribution.

The present invention therefore provides the compounds of the formula Ibelow

in which

M¹ is a metal from group IVb, Vb or VIb of the Periodic Table,

R¹ and R² are identical or different and are a hydrogen atom, aC₁-C₁₀-alkyl group, a C₁-C₁₀-alkoxy group, a C₆-C₁₀-aryl group, aC₆-C₁₀-aryloxy group, a C₂-C₁₀-alkenyl group, a C₇-C₄₀-arylalkyl group,a C₇-C₄₀-alkylaryl group, a C₈-C₄₀-arylalkenyl group or a halogen atom,

R³ and R⁴ are identical or different and are a hydrogen atom, a halogenatom, a C₁-C₁₀-alkyl group, which may be halogenated, a C₆-C₁₀-arylgroup, an —NR₂ ¹⁵, —SR¹⁵, —OSiR₃ ¹⁵, —SiR₃ ¹⁵ or —PR₂ ¹⁵ radical inwhich R¹⁵ is a halogen atom, a C₁-C₁₀-alkyl group or a C₆-C₁₀-arylgroup,

R⁵ and R⁶ are identical or different and are as defined for R³ and R⁴,with the proviso that R⁵ and R⁶ are not hydrogen,

R⁷ is

where

R¹¹, R¹² and R¹³ are identical or different and are a hydrogen atom, ahalogen atom, a C₁-C₁₀-alkyl group, a C₁-C₁₀-fluoroalkyl group, aC₆-C₁₀-aryl group, a C₆-C₁₀-fluoroaryl group, a C₁-C₁₀-alkoxy group, aC₂-C₁₀-alkenyl group, a C₇-C₄₀-arylalkyl group, a C₈-C₄₀-arylalkenylgroup or a C₇-C₄₀-alkylaryl group, or R¹¹ and R¹² or R¹¹ and R¹³, ineach case with the atoms connecting them, form a ring,

M² is silicon, germanium or tin,

R⁸ and R⁹ are identical or different and are as defined for R¹¹,

m and n are identical or different and are zero, 1 or 2, m plus n beingzero, 1 or 2, and,

the radicals R¹⁰ are identical or different and are as defined for R¹¹,R¹² and R¹³.

Alkyl is straight-chain or branched alkyl. Halogen (halogenated) isfluorine, chlorine, bromine or iodine, preferably fluorine or chlorine.

In the formula I, M¹ is a metal from group IVb, Vb or VIb of thePeriodic Table, for example titanium, zirconium, hafnium, vanadium,niobium, tantalum, chromium, molybdenum or tungsten, preferablyzirconium, hafnium or titanium.

R¹ and R² are identical or different and are a hydrogen atom, a C₁-C₁₀-,preferably C₁-C₃-alkyl group, a C₁-C₁₀-, preferably C₁-C₃-alkoxy group,a C₆-C₁₀-, preferably C₆-C₈-aryl group, a C₆-C₁₀-, preferablyC₆-C₈-aryloxy group, a C₂-C₁₀-, preferably C₂-C₄-alkenyl group, aC₇-C₄₀, preferably C₇-C₁₀-arylalkyl group, a C₇-C₄₀-, preferablyC₇-C₁₂-alkylaryl group, a C₈-C₄₀-, preferably C₈-C₁₂-arylalkenyl groupor a halogen atom, preferably chlorine.

R³ and R⁴ are identical or different and are a hydrogen atom, a halogenatom, preferably a fluorine, chlorine or bromine atom, a C₁-C₁₀-,preferably C₁-C₄-alkyl group, which may be halogenated, a C₆-C₁₀-,preferably C₆-C₈-aryl group, an —NR₂ ¹⁵, —SR¹⁵, —OSiR₃ ¹⁵, —SiR₃ ¹⁵ or—PR₂ ¹⁵ radical in which R¹⁵ is a halogen atom, preferably a chlorineatom, or a C₁-C₁₀-, preferably C₁-C₃-alkyl group or a C₆-C₁₀-,preferably C₆-C₈-aryl group. R³ and R⁴ are particularly preferablyhydrogen.

R⁵ and R⁶ are identical or different, preferably identical, and are asdefined for R³ and R⁴, with the proviso that R⁵ and R⁶ cannot behydrogen. R⁵ and R⁶ are preferably (C₁-C₄)-alkyl which may behalogenated, such as methyl, ethyl, propyl, isopropyl, butyl, isobutylor trifluoromethyl, in particular methyl.

R⁷ is

where R¹¹, R¹² and R¹³ are identical or different and are a hydrogenatom, a halogen atom, a C₁-C₁₀-, preferably C₁-C₄-alkyl group, inparticular a methyl group, a C₁-C₁₀-fluoroalkyl group, preferably a CF₃group, a C₆-C₁₀-, preferably C₆-C₈-aryl group, a C₆-C₁₀-fluoroarylgroup, preferably a pentafluorophenyl group, a C₁-C₁₀-, preferablyC₁-C₄-alkoxy group, in particular a methoxy group, a C₂-C₁₀-, preferablyC₂-C₄-alkenyl group, a C₇-C₄₀-, preferably C₇-C₁₀-arylalkyl group, aC₈-C₄₀-, preferably C₈-C₁₂-arylalkenyl group or a C₇-C₄₀-, preferablyC₇-C₁₂-alkylaryl group, or R¹¹ and R¹² or R¹¹ and R¹³, in each casetogether with the atoms connecting them, form a ring.

M² is silicon, germanium or tin, preferably silicon or germanium.

R⁷ is preferably ═CR¹¹R¹², ═SiR¹¹R¹², ═GeR¹¹R¹², —O—, —S—, ═SO, ═PR¹¹ or═P(O)R¹¹.

R⁸ and R⁹ are identical or different and are as define as for R¹¹.

m and n are identical or different and are zero, 1 or 2, preferably zeroor 1, where m plus n is zero, 1 or 2, preferably zero or 1.

The radicals R¹⁰ are identical or different and are as defined for R¹¹,R¹² and R¹³. The radicals R¹⁰ are preferably hydrogen atoms or C₁-C₁₀,preferably C₁-C₄-alkyl groups.

The particularly preferred metallocenes are thus those in which, in theformula I, M¹ is Zr or Hf, R¹ and R² are identical or different and aremethyl or chlorine, R³ and R⁴ are hydrogen, R⁵ and R⁶ are identical ordifferent and are methyl, ethyl or trifluoromethyl, R⁷ is

radical, n plus m is zero or 1, and R¹⁰ is hydrogen; in particular thecompounds I listed in the working examples.

Of the metallocenes I mentioned in the working examples,rac-dimethylsilyl(2-methyl-4,5,6,7-tetrahydro-1-indenyl)₂zirconiumdichloride,rac-ethylene(2-methyl-4,5,6,7-tetrahydro-1-indenyl)₂zirconiumdichloride,racdimethylsilyl(2-methyl-4,5,6,7-tetrahydro-1-indenyl)₂dimethylzirconiumandrac-ethylene(2-methyl-4,5,6,7-tetrahydro-1-indenyl)₂dimethylzirconiumare particularly important.

The chiral metallocenes are employed as racemates for the preparation ofhighly isotactic poly-1-olefins. However, it is also possible to use thepure R- or S-form. These pure stereoisomeric forms allow the preparationof an optically active polymer. However, the meso form of themetallocenes should be separated off since the polymerization-activecenter (the metal atom) in these compounds is no longer chiral due tomirror symmetry at the central metal, and it is therefore not possibleto produce a highly isotactic polymer.

The principle of resolution of the stereoisomers is known.

The present invention furthermore provides a process for the preparationof the metallocenes I, which comprises

a) reacting a compound of the formula II

in which R³-R¹⁰, m and n are defined in the formula I and M³ is analkali metal, preferably lithium, with a compound of the formula III

M¹X₄   (III)

in which M³ is a defined in the formula I, and X is a halogen atom,preferably chlorine, and catalytically hydrogenating the reactionproduct, or

b) reacting a compound of the formula IIa

with a compound of the formula III

M¹X₄   (III)

in which all the substituents are as defined under a), and, if desired,derivatizing the reaction product obtained under a) or b).

The synthesis is carried out under a protective gas and in anhydroussolvents. The dried salt of the formula III/IIa is added to a suspensionof the compound of the formula III in a solvent such as toluene,n-hexane, di-chloromethane, ether, THF, n-pentane or benzene, preferablydichloromethane or toluene. The reaction temperature is from −78° C. to30° C., preferably from −40° C. to 10° C. The reaction duration is from0.25 to 24 hours, preferably from 1 to 4 hours.

A further embodiment of the process according to the invention comprisesreplacing the compound III, M¹X₄, by a compound of the formula IIIa,M¹X₄L₂. In this formula, L is a donor ligand. Examples of suitable donorligands are tetrahydrofuran, diethyl ether, dimethyl ether, inter alia,preferably tetrahydrofuran (THF).

In this case, a solution of the salt of the formula II/IIa in one of theabovementioned solvents is added to a solution or suspension of acompound of the formula IIIa in a solvent such as toluene, xylene, etheror THF, preferably THF. However, an alternative procedure is tosimultaneously add both components dropwise to a solvent. This is thepreferred procedure. The reaction temperature is from −40° C. to 100°C., preferably from 0° C. to 50° C., in particular from 10° C. to 35° C.The reaction duration is from 0.25 hour to 48 hours, preferably from 1hour to 24 hours, in particular from 2 hours to 9 hours.

The hydrogenation is carried out in a dry, anhydrous solvent such asH₂CCl₂ or glyme. The reaction temperature is 20° to 70° C., preferablyfrom ambient temperature to 50° C., the pressure is from 5 to 200 bar,preferably from 20 to 120 bar, in particular from 35 to 100 bar, and thereaction duration is from 0.25 to 24 hours, preferably from 0.5 to 18hours, in particular from 1 to 12 hours. Hydrogenation reactors whichcan be used are steel autoclaves. The hydrogenation catalyst used isplatinum, platinum oxide, palladium or another conventionaltransition-metal catalyst.

The halogen derivatives obtained in this way can be converted into thealkyl, aryl or alkenyl complexes by known standard methods.

The compounds of the formulae II and IIa are synthesized bydeprotonation. This reaction is known; cf. J. Am. Chem. Soc., 112 (1990)2030-2031, ibid. 110 (1988) 6255-6256, ibid. 109 (1987), 6544-6545, J.Organomet. Chem., 322 (1987) 6570, New. J. Chem. 14 (1990) 499-503 andthe working examples.

The synthesis of the protonated forms of the compounds of these formulaehas also been described, with the difference that they are notcorrespondingly substituted in the α- and β-positions (Bull. Soc. Chim.,1967, 2954). The bridging units required for their synthesis aregenerally commercially available, but the indenyl compounds required, bycontrast, are not. Some literature references containing synthesisprocedures are indicated; the procedure for indene derivatives which arenot mentioned is analogous: J. Org. Chem., 49 (1984) 4226-4237, J. Chem.Soc., Perkin II, 1981, 403-408, J. Am. Chem. Soc., 106 (1984) 6702, J.Am. Chem. Soc., 65 (1943) 567, J. Med. Chem., 30 (1987) 1303-1308, Chem.Ber. 85 (1952) 78-85 and the working examples.

The metallocenes I can thus in principle be prepared in accordance withthe reaction scheme below:

The cocatalyst used according to the invention in the polymerization ofolefins is an aluminoxane of the formula (IV)

for the linear type and/or of the formula (V)

for the cyclic type, where, in the formulae (IV) and (V), the radicals Rmay be identical or different and are a C₁-C₆-alkyl group, a C₆-C₁₈-arylgroup or hydrogen, and p is an integer from 2 to 50, preferably from 10to 35.

The radicals R are preferably identical and are methyl, isobutyl, phenylor benzyl, particularly preferably methyl.

If the radicals R are different, they are preferably methyl and hydrogenor alternatively methyl and isobutyl, preferably from 0.01 to 40% (ofthe number of radicals R) being hydrogen or isobutyl.

The aluminoxane can be prepared in different ways by known processes.One of the methods is, for example, the reaction of analuminum-hydrocarbon compound and/or a hydridoaluminum-hydrocarboncompound with water (gaseous, solid, liquid or bound—for example aswater of crystallization) in an inert solvent (such as, for example,toluene). In order to prepare an aluminoxane containing different alkylgroups R, two different trialkylaluminum compounds (AlR₃+AlR′₃) inaccordance with the desired composition are reacted with water (cf. S.Pasynkiewicz, Polyhedron 9 (1990) 429 and EP-A 302 424).

The precise structure of the aluminoxanes IV and V is not known.

Irrespective of the preparation method, a varying content of unreactedaluminum starting compound, in free form or as an adduct, is common toall the aluminoxane solutions.

It is possible to preactivate the metallocene I using an aluminoxane ofthe formula (IV) and/or (V) before use in the polymerization reaction.This considerably increases the polymerization activity and improves theparticle morphology.

The preactivation of the transition-metal compound is carried out insolution. The metallocene is preferably dissolved in a solution of thealuminoxane in an inert hydrocarbon. Suitable inert hydrocarbons arealiphatic or aromatic hydrocarbons. Toluene is preferred.

The concentration of the aluminoxane in the solution is in the rangefrom about 1% by weight up to the saturation limit, preferably from 5 to30% by weight, in each case based on the entire solution. Themetallocene can be employed in the same concentration, but is preferablyemployed in an amount of from 10⁻⁴−1 mol per mole of aluminoxane. Thepreactivation time is from 5 minutes to 60 hours, preferably from 5 to60 minutes. The preactivation temperature is from −78° C. to 100° C.,preferably from 0 to 70° C.

The metallocene can also be prepolymerized or applied to a support. Theprepolymerization is preferably carried out using the olefin (or one ofthe olefin) employed in the polymerization.

Examples of suitable supports are silica gels, aluminum oxides, solidaluminoxane or other inorganic support materials. Another suitablesupport material is a polyolefin powder in finely divided form.

A further possible variation of the process comprises using a salt-likecompound of the formula R_(x)NH_(4−x)BR′₄ or of the formula R₃PHBR′₄ ascocatalyst instead of or in addition to an aluminoxane. x here is 1, 2or 3, the R radicals are identical or different and are alkyl or aryl,and R′ is aryl, which may also be fluorinated or partially fluorinated.In this case, the catalyst comprises the product of the reaction of ametallocene with one of said compounds (cf. EP-A 277 004).

The polymerization or copolymerization is carried out in a known mannerin solution, in suspension or in the gas phase, continuously orbatchwise, in one or more steps, at a temperature of from 0° to 150° C.,preferably from 30° to 80° C. Olefins of the formula R^(a)—CH═CH—R^(b)are polymerized or copolymerized. In this formula, R^(a) and R^(b) areidentical or different and are a hydrogen atom or an alkyl radicalhaving 1 to 14 carbon atoms.

However, R^(a) and R^(b), together with the carbon atoms connectingthem, may also form a ring. Examples of such olefins are ethylene,propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, norborneneor norbornadiene. In particular, propylene and ethylene are polymerized.

The molecular weight regulator added, if necessary, is hydrogen. Theoverall pressure in the polymerization system is from 0.5 to 100 bar.The polymerization is preferably carried out in the industriallyparticularly interesting pressure range of from 5 to 64 bar.

The metallocene is used in a concentration, based on the transitionmetal, of from 10⁻³ to 10⁻⁸, preferably from 10⁻⁴ to 10⁻⁷ mol oftransition metal per dm³ of solvent or per dm³ of reactor volume. Thealuminoxane is used in a concentration of from 10⁻⁵ to 10⁻¹ mol,preferably from 10⁻⁴ to 10² mol, per dm³ of solvent or per dm³ ofreactor volume. In principle, however, higher concentrations are alsopossible.

If the polymerization is carried out as a suspension or solutionpolymerization, an inert solvent which is customary for the Zieglerlow-pressure process is used. For example, the polymerization is carriedout in an aliphatic or cycloaliphatic hydrocarbon; examples of thesewhich may be mentioned are butane, pentane, hexane, heptane, isooctane,cyclohexane and methylcyclohexane.

It is also possible to use a petroleum ether or hydrogenated diesel oilfraction. Toluene can also be used.

The polymerization is preferably carried out in the liquid monomer.

If inert solvents are used, the monomers are metered in in gaseous orliquid form.

The polymerization can have any desired duration since the catalystsystem to be used according to the invention exhibits only a lowtime-dependent drop in polymerization activity.

The process is distinguished by the fact that the metallocenes accordingto the invention give, in the industrially interesting temperature rangeof between 30° and 80° C., polymers of high molecular weight, highstereospecificity, narrow molecular weight dispersity and, inparticular, high melting point, which is to say high crystallinity andhigh hardness.

The examples below are intended to illustrate the invention in greaterdetail.

The following abbreviations are used:

VN = viscosity number in cm³/g M_(w) = weight average molecular weightdetermined by gel M_(w)/M_(n) = molecular weight dispersity permeationchro- matography II = isotactic index (II = mm + ½ mr), determined by¹³C-NMR spectroscopy n_(iso) = length of the isotactic blocks (inpropylen units) (n_(iso) = 1 + 2 mm/mr), determined by ¹³C-NMRspectroscopy

The melting points and heats of melting Δ H_(melt) were determined usingDSC (heating and cooling rate 20° C./min).

Synthesis of the starting substances

I) Synthesis of 2-Me-indene

110.45 g (0.836 mol) of 2-indanone were dissolved in 500 ml of diethylether, and 290 cm³ of 3N (0.87 mol) ethereal methylGrignard solutionwere added dropwise at such a rate that the mixture refluxed gently.After the mixture had boiled for 2 hours under gentle reflux, it wastransferred onto an ice/hydrochloric acid mixture, and a pH of 2-3 wasestablished using ammonium chloride. The organic phase was separatedoff, washed with NaHCO₃ and sodium chloride solution and dried, giving98 g of crude product (2-hydroxy-2-methylindane), which was not purifiedfurther.

This product was dissolved in 500 cm³ of toluene, 3 g ofp-toluenesulfonic acid were added, and the mixture was heated on a waterseparator until the elimination of water was complete, and wasevaporated, the residue was taken up in dichloromethane, thedichloromethane solution was filtered through silica gel, and thefiltrate was distilled in vacuo (80° C./10 mbar).

Yield: 28.49 g (0.22 mol/26%).

The synthesis of this compound is also described in: C. F. Koelsch, P.R. Johnson, J. Am. Chem. Soc., 65 (1943) 567-573.

II) Synthesis of (2-Me-indene)₂SiMe₂

13 g (100 mmol) of 2-Me-indene were dissolved in 400 cm³ of diethylether, and 62.5 cm³ of 1.6N (100 mmol) n-butyllithium/n-hexane solutionwere added dropwise over the course of 1 hour with ice cooling, and themixture was then stirred at ˜35° C. for a further 1 hour.

6.1 cm³ (50 mmol) of dimethyldichlorosilane were introduced into 50 cm³of Et₂O, and the lithio salt solution was added dropwise at 0° C. overthe course of 5 hours, the mixture was stirred overnight at roomtemperature and left to stand over the weekend.

The solid which had deposited was filtered off, and the filtrate wasevaporated to dryness. The product was extracted using small portions ofn-hexane, and the extracts were filtered and evaporated, giving 5.7 g(18.00 mmol) of white crystals. The mother liquor was evaporated, andthe residue was then purified by column chromatography (n-hexane/H₂CCl₂9:1 by volume), giving a further 2.5 g (7.9 mmol/52%) of product (as anisomer mixture).

R_(f)(SiO₂; n-hexane/H₂CCl₂ 9:1 by volume)=0.37.

The ¹H-NMR spectrum exhibits the signals expected for an isomer mixturewith respect to shift and integration ratio.

III) Synthesis of (2-Me-Ind)₂CH₂CH₂

3 g (23 mmol) of 2-Me-indene were dissolved in 50 cm³ of THF, 14.4 cm³of 1.6N (23.04 mmol) n-butyllithium/n-hexane solution were addeddropwise, and the mixture was then stirred at 65° C. for 1 hour. 1 cm³(11.5 mmol) of 1,2-dibromoethane was then added at −78° C., and themixture was allowed to warm to room temperature and was stirred for 5hours. The mixture was evaporated, and the residue was purified bycolumn chromatography (SiO₂; n-hexane/H₂CCl₂ 9:1 by volume).

The fractions containing the product were combined and evaporated, theresidue was taken up in dry ether, the solution was dried over MgSO₄ andfiltered, and the solvent was stripped off.

Yield: 1.6 g (5.59 mmol/49%) of isomer mixture R_(f) (SiO₂;n-hexane/H₂CCl₂ 9:1 by volume)=0.46.

The ¹H-NMR spectrum corresponds to expectations for an isomer mixture insignal shift and integration.

Synthesis of the metallocenes I

IV) rac-Dimethysilyl(2-Me-4,5,6,7-tetrahydro-1-indenyl)₂zirconiumdichloride

a. Synthesis of the precursorrac-dimethylsilyl(2-Me-1-indenyl)₂zirconium dichloride

1.68 g (5.31 mmol) of the chelate ligand dimethylsilyl(2-methylindene)₂were introduced into 50 cm³ of THF, and 6.63 cm³ of a 1.6N (10.61 mmol)n-BuLi/n-hexane solution were added dropwise at ambient temperature overthe course of 0.5 hour. The mixture was stirred for 2 hours at about 35°C., the solvent was stripped off in vacuo, and the residue was stirredwith n-pentane, filtered off and dried.

The dilithio salt obtained in this way was added at −78° C. to asuspension of 1.24 g (5.32 mmol) of ZrCl in 50 cm³ of CH₂Cl₂, and themixture was stirred at this temperature for 3 hours. The mixture wasthen warmed to room temperature overnight and evaporated. The ¹H-NMRspectrum showed, in addition to the presence of some ZrCl₄(thf)₂, arac/meso mixture. After stirring with n-pentane and drying, the solid,yellow residue was suspended in THF, filtered off and examined by NMRspectroscopy. These three working steps were repeated a number of times;finally, 0.35 g (0.73 mmol/14%) of product was obtained in which the racform, according to ¹H-NMR, was enriched to more than 17:1.

The compound exhibited a correct elemental analysis and the followingNMR signals (CDCl₃, 100 MHz): δ=1.25 (s, 6H, Si-Me); 2.18 (s, 6H, 2-Me),6.8 (s, 2H, 3-H-Ind); 6.92-7.75 (m, 8H, 4-7-H-Ind).

b. Synthesis of the end product

0.56 g (1.17 mmol) of the precursorrac-dimethylsilyl(2-Me-1-indenyl)₂zirconium dichloride were dissolved in70 cm³ of CH₂Cl₂ and the solution was introduced, together with 40 mg ofPtO₂, into a 200 cm³ NOVA stirred autoclave. The mixture was thenstirred at room temperature for 4 hours under an H₂pressure of 40 bar.The filtrate was evaporated, the residue was washed withtoluene/n-hexane (1:2 by volume), filtered and evaporated. N-pentane wasadded, and the suspension obtained was filtered off and dried. The yieldwas 0.34 g (0.7 mmol/60%). The ¹H-NMR spectrum (CD₂Cl₂, 100 MHz) showedthe following signals:

δ=0.90 (s, 6H, Me-Si); 1.43-1.93 (m, 8H, indenyl-H); 2.10 (s, 6H, 2-Me);2.44-3.37 (m, 8H, indenyl-H); 6.05 (s, 2H, 3-H-Ind).

V) Synthesis of rac-ethylene(2-Me-4,5,6,7-tetrahydrol-indenyl)₂zirconiumdichloride

a. Synthesis of the precursor rac-ethylene(2-Me-1-indenyl)₂zirconiumdichloride

14.2 cm³ of 2.5N (35.4 mmol) n-BuLi/n-hexane solution were addeddropwise over the course of 1 hour at room temperature to 5.07 g (17.7mmol) of the ligand ethylene(2-methylindene)₂ in 200 cm³ of THF, and themixture was then stirred at about 50° C. for 3 hours. A precipitatewhich formed temporarily dissolved again. The mixture was left to standovernight.

6.68 g (17.7 mmol) of ZrCl₄thf)₂ in 250 cm³ of THF were added dropwise,simultaneously with the above dilithio salt solution, to about 50 cm³ ofTHF at 50° C., and the mixture was then stirred at this temperature for20 hours. The toluene extract of the evaporation residue was evaporated.The residue was extracted with a little THF, and the product wasrecrystallized from toluene, giving 0.44 g (0.99 mmol/5.6%) of productin which the rac form was enriched to more than 15:1.

The compound exhibited a correct elemental analysis and the followingNMR signals (CDCl₃, 100 MHz): δ=2.08 (2s, 6H, 2-Me); 3.45-4.18 (m, 4H,—CH₂CH₂—); 6.65 (2H, 3-H-Ind); 7.05-7.85 (m, 8H, 4-7-H-Ind).

b. Synthesis of the end product

56 g (1.25 mmol) of rac-ethylene(2-Me-1-indenyl)₂zirconium dichloridewas dissolved in 50 cm³ of CH₂Cl₂, and the solution was introduced,together with 40 mg of PtO₂, into a 200 cm³ NOVA stirred autoclave. Themixture was then stirred at room temperature for 2 hours under an H₂pressure of 40 bar and evaporated to dryness, and the residue wassublimed in a high vacuum at a bath temperature of about 100° C., giving0.46 g (1.01 mmol/81%) of product. The elemental analysis was correct,and the ¹H-NMR spectrum showed the following signals: δ=1.46-1.92 (m,8H, indenyl-H), 2.14 (s, 6H, 2-Me); 2.49-2.73 (m, 6H, indenyl-H and—CH₂CH₂—), 2.89-3.49 (m, 6H, indenyl-H); 6.06 (s, 2H, 3-H-Ind).

VI) Me₂Zr[(2-Me-4,5,6,7-H₄-Ind)₂CH₂CH₂]

5 cm³ of 1.6N (8 mmol) of ethereal methyllithium solution were addeddropwise at −50° C. to 1.27 g (2.79 mmol) ofCl₂Zr[(2-Me-4,5,6,7-H₄-Ind)₂CH₂CH₂] in 20 cm³ of Et₂O, and the mixturewas then stirred for 1 hour at −10° C. The solvent was replaced byn-hexane, and the mixture was stirred for a further 2 hours at roomtemperature, filtered and evaporated.

Yield: 1 g (2.40 mmol/86%); correct elemental analysis.

VII) Me₂Zr[(2-Me-4,5,6,7-H₄-Ind)₂SiMe₂]

4.3 cm³ of 1.6N (6.88 mmol) of ethereal methyllithium solution wereadded dropwise over the course of 15 minutes at −35° C. to 1.33 g (2.74mmol) of Cl₂Zr[(2-Me-4,5,6,7-H₄-Ind)₂SiMe₂] in 25 cm³ of Et₂O. Themixture was stirred for 1 hour, the solvent was replaced by n-hexane,the mixture was stirred for 2 hours at 10° C. and then filtered, thefiltrate was evaporated, and the residue was sublimed in a high vacuum.

Yield: 1.02 g (2.49 mmol/89%); correct elemental analysis

VIII) Cl₂Zr[(2-Me-4,5,6,7-H₄-Ind)₂SiMePh]

1.5 g (2.78 mmol) of Cl₂Zr[(2-Me-Ind)₂SiMePh] and 60 mg of PtO₂ in 80cm³ of H₂CCl₂ were hydrogenated for 5 hours at 40° C. in a stirredautoclave under an H₂ pressure of 30 bar. The mixture was filtered, thesolvent was stripped off, and the residue was sublimed in a high vacuum.

Yield: 0.71 g (1.30 mmol/47%); correct elemental analysis

IX) Cl₂Zr[(2-Me-4,5,6,7-H₄-Ind)₂SiPh₂]

0.8 g (1.33 mmol) of Cl₂Zr[(2-Me-Ind)₂SiPh₂], dissolved in 50 cm³ ofH₂CCl₂, were stirred for 3 hours at 40° C. with 30 mg of Pt under an H₂pressure of 50 bar. The mixture was filtered, the filtrate wasevaporated, the residue was washed with warm n-hexane, the mixture wasfiltered, and the filtrate was evaporated.

Yield: 0.36 g (0.59 mmol/44%); correct elemental analysis

X) Cl₂Zr[(2-Et-4,5,6,7-H-Ind)₂CH₂CH₂]

1.09 g (2.30 mmol) of Cl₂Zr[(2-Et-Ind)₂CH₂CH₂] in 80 cm³ of H₂CCl₂ werehydrogenated for 1 hour at ambient temperature together with 50 mg ofPtO₂ under an H₂ pressure of 80 bar. The mixture was filtered, thefiltrate was evaporated, and the residue was sublimed in a high vacuum.

Yield: 0.94 g (1.95 mmol/85%); correct elemental analysis

XI) Cl₂Zr[(2-Et-4,5,6,7-H₄-Ind)₂SiMe₂]

2.00 g (3.96 mmol) of Cl₂Zr[(2-Et-Ind)₂SiMe₂] in 100 cm³ of H₂CCl₂ werehydrogenated for 3 hours at 35° C. together with 60 mg of PtO₂ under anH₂ pressure of 50 bar. The mixture was filtered, the filtrate wasevaporated, and the residue was recrystallized from n-pentane.

Yield: 1.41 g (2.75 mmol/69%); correct elemental analysis

XII) Cl₂Zr[(2-Me-4,5,6,7-H₄-Ind)₂CHMeCH₂]

0.80 g (1.73 mmol) of Cl₂Zr[(2-Me-Ind)₂CHMeCH₂] in 40 cm³ of H₂CCl₂ werestirred for 1 hour at ambient temperature together with 30 mg of PtO₂under an H₂ pressure of 80 bar, the mixture was then filtered, thefiltrate was evaporated, and the residue was sublimed.

Yield: 0.55 g (1.17 mmol/68%); correct elemental analysis

XIII) Cl₂Zr[(2-Me-4,5,6,7-H₄-Ind)₂CMe₂]

0.3 g (0.65 mmol) of Cl₂Zr[(2-Me-Ind)₂CMe₂] in 30 cm³ of H₂CCl₂ werehydrogenated for 1 hour at ambient temperature together with 30 mg of Ptunder an H₂ pressure of 70 bar. The solvent was stripped off, and theresidue was sublimed in a high vacuum.

Yield: 0.21 g (0.45 mmol/69%); correct elemental analysis

Abbreviations:

Me=methyl, Et=ethyl, Bu=butyl, Ph=phenyl,

Ind=indenyl, THF=tetrahydrofuran, PP=polypropylene,

PE=polyethylene.

Metallocenes I as catalysts for the polymerization of olefins

EXAMPLE 1

12 dm³ of liquid propylene were introduced into a dry 24 dm³ reactorwhich had been flushed with nitrogen. 35 cm³ of a toluene solution ofmethylaluminoxane (corresponding to 52 mmol of Al, mean degree ofoligomerization n=17) were then added, and the batch was stirred at 30°C. for 15 minutes. In parallel, 5.3 mg (0.011 mmol) ofrac-dimethylsilyl(2-Me-4,5,6,7-tetrahydro-1-indenyl)₂zirconiumdichloride were dissolved in 13.5 cm³ of a toluene solution ofmethylaluminoxane (20 mmol of Al) and preactivated by standing for 15minutes. The solution was then introduced into the reactor and thepolymerization system was heated to 70° C. (over the course of 5minutes) and kept at this temperature for 3 hours by cooling.

The activity of the metallocene was 50.3 kg of PP/g of metallocene×h.

VN=37 cm³/g M_(w)=24 300 g/mol; M_(w)M_(n)=2.4; II=96.0%; n_(iso)=62;M.p.=150° C.; ΔH_(melt)=104 J/g.

Example 2

Example 1 was repeated, but 19.5 mg (0.04 mmol) of the metallocene wereemployed, and the polymerizaton temperature was 50° C.

The activity of the metallocene was 18.8 kg of PP/g of metallocene×h.

VN=72 cm³/g; M₂=64 750 g/mol; M_(w)/Mn=2.1; II=96.0%; n_(iso)=64;M.p.=154° C; ΔH_(melt)=109.5 J/g.

Example 3

Example 1 was repeated, but 58.0 mg (0.12 mmol) of the metallocene wereused and the polymerization temperature was 30° C.

The activity of the metallocene was 9.7 kg of PP/g of metallocene×h.

VN=152 cm³/g; M_(w)=171 000 g/mol; M_(w)/M_(n)=2.2; II=99.9%;n_(iso)=>500; M.p.=160° C.; ΔH_(melt)=103 J/g.

Comparative Examples A-H

Examples 1 to 3 were repeated, but the metallocenesdimethylsilyl(2-Me-1-indenyl)₂zirconium dichloride (metallocene 1),dimethylsilyl(4,5,6,7-tetrahydro-1-indenyl)₂zirconium dichloride(metallocene 2) and dimethylsilyl(1-indenyl)₂zirconium dichloride(metallocene 3) were used.

Comp. Polym. M.p. ΔH_(melt) Ex. Metallocene temp. [° C.] n_(iso) [° C.][J/g] A 1 70 38 145 86.6 B 1 50 48 148 88.1 C 1 30 48 152 90.2 D 2 70 34141 — E 2 50 38 143 — F 3 70 32 140 — G 3 50 34 142 — H 3 30 37 145 —

Comparison of Comparative Examples F/G with D/E confirms the positiveeffect of the 4,5,6,7-tetrahydroindenyl ligand compared with indenyl,and Comparative Examples F/G/H compared with A/B/C show the positiveeffect of the substitution in the 2-position of the indenyl ligand.

In comparison with Examples 1 to 3, however, only the combination ofsubstitution in the 2-position together with the tetrahydroindenylsystem results in very high melting points and heats of melting and thusin high crystallinity and hardness of the polymers.

Example 4

Example 1 was repeated, but 6.8 mg (0.015 mmol) ofethylene(2-Me-4,5,6,7-tetrahydro-1-indenyl)₂zirconium dichloride wereemployed.

The metallocene activity was 72.5 kg of PP/g of metallocene×h.

VN=35 cm³/g; M_(w)=20 750 g/mol; M_(w)/M_(n)=1.9; II=94.5%; n_(iso)=34;M.p.=141° C.; ΔH_(melt)=92.4 J/g.

Example 5

Example 4 was repeated, but 28.1 mg (0.062 mmol) of the metallocene wereused and the polymerization temperature was 50° C.

The metallocene activity was 28.5 kg of PP/g of metallocene×h.

VN=51 cm³/g; M_(w)=28 200 g/mol; M_(w)/M_(n)=2.2; II=94.8%; n_(iso)=35;M.p.=143° C.; ΔH_(melt)=97.9 J/g.

Example 6

Example 4 was repeated, but 50 mg (0.110 mmol) of the metallocene wereused and the polymerization temperature was 30° C.

The metallocene activity was 10.9 kg of PP/g of metallocene×h.

VN=92 cm³/g; M_(w)=93 800 g/mol; M_(w)/M_(n)=2.2; II=95.5%; n_(iso)=48;M.p.=151° C.; ΔH_(melt)=99.0 J/g.

Comparative Examples I-O

Examples 4 to 6 were repeated, but the metallocenesethylene(1-indenyl)₂zirconium dichloride (metallocene 4) andethylene(2-Me-1-indenyl)₂zirconium dichloride (metallocene 5) were used.

Comp. Polym. M.p. ΔH_(melt) Ex. Metallocene temp. [° C.] n_(iso) [° C.][J/g] I 4 70 23 132 64.9 K 4 50 30 138 78.1 L 4 30 29 137 78.6 M 5 70 25134 77.0 N 5 50 30 13S 7S.9 O 5 30 32 138 7S.6

Comparison of Comparative Examples I to O with Examples 4 to 6 confirmsthe effect of the substitution in the 2-position together with the useof the tetrahydroindenyl system. n_(iso), melting point and heat ofmelting are significantly higher in each of Examples 4-6, and thecrystallinity and hardness of the polymers are thus also significantlyimproved.

We claim:
 1. A compound of the formula I for preparing essentiallyisotactic olefin polymers

in which M¹ is a metal from group IVb, Vb or VIb of the Periodic TableR¹ and R² are identical or different and are a hydrogen atom, aC₁-C₁₀-alkyl group, a C₁-C₁₀-alkoxy group, a C₆-C₁₀-aryl group, aC₆-C₁₀-aryloxy group, a C₂-C₁₀-alkenyl group, a C₇-C₄₀-arylalkyl group,a C₇-C₄₀-alkylaryl group, a C₈-C₄₀-arylalkenyl group or a halogen atom,R³ and R⁴ are identical or different and are a hydrogen atom, a halogenatom, a halogen atom, a C₁-C₁₀-alkyl group, which is optionallyhalogenated, a C₆-C₁₀-aryl group, an —NR₂ ¹⁵, —SR¹⁵, —OSiR₃ ¹⁵, —SiR₃ ¹⁵or —PR₂ ¹⁵ radical in which R¹⁵ is a halogen atom, a C₁-C₁₀-alkyl groupor a C₆-C₁₀-aryl group, R⁵ and R⁶ are identical or different and are asdefined for R³ and R⁴, with the proviso that R⁵ and R⁶ are not hydrogen,R⁷ is

where R¹¹, R¹² and R¹³ are identical or different and are a hydrogenatom, a halogen atom, a C₁-C₁₀-alkyl group, a C₁-C₁₀-fluoroalkyl group,a C₆-C₁₀-aryl group, a C₆-C₁₀-fluoroaryl group, a C₁-C₁₀-alkoxy group, aC₂-C₁₀-alkenyl group, a C₇-C₄₀-arylalkyl group, a C₈-C₄₀-arylalkenylgroup or a C₇-C₄₀-alkylaryl group, or R¹¹ and R¹² or R¹¹ and R¹³, ineach case with the atoms connecting them, form a ring, M² is silicon,germanium or tin, R⁸ and R⁹ are identical or different and are asdefined for R¹¹ m and n are identical or different and are zero, 1 or 2,m plus n being zero, 1 or 2, and the radicals R¹⁰ are identical ordifferent and are as defined for R¹¹, R¹² and R¹³.
 2. A compound of theformula I as claimed in claim 1, wherein, in the formula I, M¹ is Zr orHf, R¹ and R² are identical or different and are methyl or chlorine, R³or R⁴ are hydrogen, R⁵ and R⁶ are identical or different and are methyl,ethyl or trifluoromethyl, R⁷ is a

n plus m is zero or 1, and R¹⁰ is hydrogen.
 3. A compound of the formulaI as claimed in claim 1 wherein the compound israc-dimethylsilyl(2-methyl-4,5,6,7-tetrahydro-1-indenyl)₂zirconiumdichloride, rac-ethylene(2-methyl4,5,6,7-tetrahydro-1-indenyl)₂zirconiumdichloride, rac-dimethylsilyl(2-methyl-4,5,6,7-tetrahydro-1-indenyl)₂dimethylzirconium orrac-ethylene(2-methyl-4,5,6,7-tetrahydro-1-indenyl)₂dimethylzirconium.4. A compound as claimed 1, wherein M¹ is zirconium, hafnium ortitanium.
 5. A compound as claimed in claim 1, wherein R¹ and R² areidentical or different and are a hydrogen atom, a C₁-C₃-alkyl group, aC₁-C₃-alkoxy group, a C₆-C₈-aryl group, a C₆-C₈-aryloxy group, aC₂-C₄-alkenyl group, a C₇-C₁₀-arylalkyl group, a C₇-C₁₂-alkylaryl group,a C₈-C₁₂-arylalkenyl group or chlorine.
 6. A compound as claimed inclaim 1, wherein R³ and R⁴ are identical or different and are a hydrogenatom, a fluorine, chlorine or bromine atom, a C₁-C₄-alkyl group whichmay be halogenated, a C₆-C₈-aryl group, a —NR₂ ¹⁵, —SR¹⁵, —OSiR₃ ¹⁵,—SiR₃ ¹⁵ or —PR₂ ¹⁵ radical in which R¹⁵ is a chlorine atom, or aC₁-C₃-alkyl group or a C₆-C₈-aryl group.
 7. A compound as claimed inclaim 1, wherein R³ and R⁴ are hydrogen.
 8. A compound as claimed inclaim 1, wherein R⁵ and R⁶ are identical.
 9. A compound as claimed inclaim 1, wherein R⁵ and R⁶ are (C₁-C₄)-alkyl, which may be halogenatedwith methyl.
 10. A compound as claimed in claim 1, wherein R¹¹, R¹² andR¹³ are identical or different and are a hydrogen atom, a halogen atom,a C₁-C₄-alkyl group, a CF₃ group, a C₆-C₈-aryl group, apentafluorophenyl group, a C₁-C₄-alkoxy group, a C₂-C₄-alkenyl group, aC₇-C₁₀-arylalkyl group, a C₈-C₁₂-arylalkenyl group or a C₇-C₁₄-alkylarylgroup, or R¹¹ and R¹² or R¹¹ and R¹³, in each case together with theatoms connecting them, form a ring.
 11. A compound as claimed in claim1, wherein M² is silicon or germanium.
 12. A compound as claimed inclaim 1, wherein R⁷ is ═CR¹¹R¹², ═SiR¹¹R¹², ═GeR¹¹R¹², —O—, —S—, ═SO,═PR¹¹ or ═P(O)R¹¹.
 13. A compound as claimed in claim 1, wherein m and nare identical or different and are zero or
 1. 14. A compound as claimedin claim 1, wherein m plus n is zero or
 1. 15. A compound as claimed inclaim 1, wherein R¹⁰ is hydrogen or C₁-C₄-alkyl groups.
 16. A polyolefinmade by polymerizing an olefin in the presence of a combinationcomprising a metallocene compound and a cocatalyst, said metallocenecompound being a compound of the formula I:

in which M ¹ is a metal from group IVb, Vb or VIb of the Periodic TableR ¹ and R ² are identical or different and are a hydrogen atom, a C ₁ -C₁₀-alkyl group, a C ₁ -C ₁₀-alkoxy group, a C ₆ -C ₁₀-aryl group, a C ₆-C ₁₀-aryloxy group, a C ₂ -C ₁₀-alkenyl group, a C ₇ -C ₄₀-arylalkylgroup, a C ₇ -C ₄₀-alkylaryl group, a C ₈ -C ₄₀-arylalkenyl group or ahalogen atom, R ³ and R ⁴ are identical or different and are a hydrogenatom, a halogen atom, a C ₁ -C ₁₀-alkyl group, which is optionallyhalogenated, a C ₆ -C ₁₀-aryl group, an —NR ₂ ¹⁵ , —SR ¹⁵ , —OSiR ₃ ¹⁵ ,—SiR ₃ ¹⁵ or —PR ₂ ¹⁵ radical in which R ¹⁵ is a halogen atom, a C ₁ -C₁₀-alkyl group or a C ₆ -C ₁₀-aryl group, R ⁵ and R ⁶ are identical ordifferent and are as defined for R ³ and R ⁴ , with the proviso that R ⁵and R ⁶ are not hydrogen,

where R ¹¹ , R ¹² and R ¹³ are identical or different and are a hydrogenatom, a halogen atom, a C ₁ -C ₁₀-alkyl group, a C ₁ -C ₁₀-fluoroalkylgroup, a C ₆ -C ₁₀-aryl group, a C ₆ -C ₁₀-fluoroaryl group, a C ₁ -C₁₀-alkoxy group, a C ₂ -C ₁₀-alkenyl group, a C ₇ -C ₄₀-arylalkyl group,a C ₈ -C ₄₀-arylalkenyl group or a C ₇ -C ₄₀-alkylaryl group, or a pairof substituents R ¹¹ and R ¹² or R ¹¹ and R ¹³ in each case with theatoms connecting them, form a ring, M ² is silicon, germanium or tin, R⁸ and R ⁹ are identical or different and are as defined for R ¹¹ m and nare identical or different and are zero, 1 or 2, m plus n being zero, 1or 2, and the radicals R ¹⁰ are identical or different and are asdefined for R ¹¹ , R ¹² and R ¹³ , except that at least one of the R ¹⁰radicals is not hydrogen.
 17. The polyolefin as claimed in claim 16,wherein said combination comprises said metallocene compound of formulaI and an aluminoxane.